The present invention relates generally to shrink films, and more particularly to monoaxially oriented shrink films.
Various films and laminates have been proposed for use particularly as label material for the labels of beverage bottles and the like. These films or laminates are preferably monoaxially oriented in order to permit a tight label to be produced around the bottle or vessel, without the undesirable wrinkling and shrinking of the label which would occur with a biaxially oriented film. The films could also be used to produce band type seals for tamper evidence.
The label material ideally possesses several properties making it particularly useful for this end use.
For example, the material should have the required stiffness (i.e. high modulus) to permit the use of the film in a rollstock form in conjunction with label manufacturing apparatus. Lower modulus material would not be useful in such apparatus.
Suitable material should also possess surface properties that allow printing of the label with information such as verbal and graphic trademarks, ingredients, and other information directed to the contents and capacity of the vessel.
It may additionally be desirable to have a film with good optical properties.
Of interest is U.S. Pat. No. 4,188,443 issued to Mueller et al wherein a five-layer film has two inner layers comprising ethylene vinyl acetate copolymer, and skin or outer layers comprising an ethylene propylene copolymer.
Of interest is U.S. Pat. No. 4,355,076 issued to Gash wherein a monoaxially oriented polypropylene film may be laminated to a monoaxially oriented high density polyethylene film, said films produced by e.g. tubular blowing.
It is therefore an object of the present invention to provide a thermoplastic film useful in forming labels or tamper evidence bands for vessels such as bottles, cans, and the like.
It is also an object of the present invention to provide such a label which can be monoaxially oriented.
It is an additional object of the present invention to provide such a film with relatively high modulus properties.
It is still another object of the present invention to provide such a film with good printability.
It is also an object of the present invention to provide a film having excellent optical properties.
Polyvinyl chloride (PVC) materials are commonly used in many packaging applications. However, a monoaxially oriented shrink film is needed for labeling and tamper evident banding of bottles and cans. The recycling of polyester bottles and cans requires a label material with a specific gravity less than 1.0. PVC has a specific gravity greater than 1.0, making this material undesirable in such applications.
It is therefore still another object of the present invention to provide a monoaxially oriented shrink film having a composite specific gravity of less than about 1.0.